1. Field of the Invention
The present invention relates to cutting tools, namely inserts for machine tools, and more particularly, to small size inserts for grooving and turning.
2. Description of Related Art
The art of cutting grooves in a workpiece using a cutting tool, and particularly using an insert secured in a toolholder is well known. The use of an insert in a toolholder for turning, i.e., removing portions of material from a rotating workpiece by causing the insert to traverse along a portion of the longitudinal surface of the workpiece while the insert is sequentially advanced into the surface of the workpiece, is also known.
In one method of securing the insert during its use, particularly for grooving, cutting or threading, the insert is clamped adjacent one side of a toolholder. In this arrangement the toolholder has a nest or pocket formed by a bottom wall and a side wall, and the insert is held in position by a top clamp. Such an arrangement is illustrated in U.S. Pat. No. 3,754,309, issued to Jones et al. on Aug. 28, 1973.
Turning, for example in a lathe, advantageously is performed by traversing and removing material from the workpiece in both longitudinal directions. However, attempts to use the same insert within a holder for both grooving and turning, especially during turning in both directions, presents problems in securely and accurately maintaining the insert in position during these operations. In particular, during turning, and most especially upon the workpiece being traversed in the direction outwardly from that side of the holder to which the insert is clamped, the outward end of the insert held by a clamp to the toolholder tends to slip or rotate sideways due to the lateral force of the workpiece on the outward end of the insert. This is particularly the case where the bottom insert supporting surface of the holder is planar and perpendicular to the sides as in U.S. Pat. No. 3,754,309. Even where the bottom insert supporting surface of the holder is not planar, but is angled as in U.S. Pat. No. 6,000,885, issued to Erickson on Dec. 14, 1999, the insert tends to slip or rotate from the holder.
Attempts have been made to overcome the tendency of the insert to slip or rotate in the holder due to lateral force on the insert, for example by forming a diagonal notch in the insert and angling the clamp element to engage the notch and by forming recessed angled portions in the top and/or bottom surfaces of the insert, as in U.S. Pat. Nos. 3,754,309 and 6,000,885. However, such attempts have generally been imperfect to counter the force exerted on the insert as explained in U.S. Pat. No. 6,000,885. Furthermore, the attempts to date have not been applicable to small-size inserts. Small-size inserts are inserts having grooving widths in the range of from about 0.004 inch to about 0.150 inch and a body width in the range of 0.15 inch, for example 0.155 inch. Due to the small size of these inserts, it is impractical to attempt to form diagonal notches and recessed portions in the shank portion of the insert, particularly where the insert is formed of a material such as carbide or of hardened steel.
It is of further utility for inserts to have the capability of being interchangeably mounted in parallel to the longitudinal axis to one side of a toolholder or the other, that is “right hand” or “left hand”, or facing to the right or to the left when installed on a toolholder perpendicular to the longitudinal axis of the toolholder for such operations as internal boring.
It is further advantageous in many applications for inserts to have dual cutting regions or heads, for example, so that the insert life can be extended by employing the second cutting head when the first head becomes dull or chipped through use. With some dual head insert configurations, the insert must be inverted as well as reversed in order to employ the second head, as in U.S. Pat. No. 4,669,924, issued to Benson on Jun. 2, 1987, and in U.S. Pat. No. 6,000,885, noted above.
Thus, there exists a need for small-sized inserts which are adapted to resist forces exerted on the insert, particularly during turning.
There is a further existing need for small size inserts which can be mounted on either the right-hand or the left-hand portions of a toolholder to facilitate use of existing toolholders which may be mounted to the machine tool, for particular operations, without the need for changing to a toolholder of the alternate hand configuration, e.g., right-hand to left-hand toolholders. A further need is for inserts with dual cutting heads which can be employed without inverting the insert, thus facilitating mounting the insert to a toolholder. A still further need is for inserts with provision for preventing rearward movement of the insert with respect to the machine tool when in use. Unwanted rearward movement of the insert in the toolholder with respect to the machine tool is undesirable as it may cause the depth of the cut or grooving and/or turning to be in error, and often causes downtime due to the necessity to remount the insert and perhaps require recalibration of the tool to ensure its accurate operation.